Ni on silica-magnesia-zirconia catalytic compositions used in reforming with steam



July 22, 1969 J. HOUSSET ET AL 3,45?,192

Ni ON SILICA-MAGNESIA-ZIRCONIA CATALYTIC COMPOSITIONS USED IN REFORMINGWITH STEAM Filed Sept. 7, 1965 Sen P-P w US. Cl. 252457 9 ClaimsABSTRACT OF THE DISCLOSURE Catalytic compositions suitable for use inthe steam reforming of hydrocarbons heavier than methane and optronallyunsaturated, comprising nickel as the active metal between 140% byweight calculated as nickel oxide and a mixture of silicon dioxide,magnesium oxide and zirconium dioxide as the support, the magnesiumoxideto zirconium oxide ratio by weight being between 1.7 and 2, and themagnesium oxide to silicon dioxide ratio by weight being between 4.5 and5, these compositions being disposed inside the reforming zone, in thedirection of flow of the gas, in several layers having an increasingcontent of nickel oxide adapted to the evolution of reaction.

The present invention relates to new catalytic compositions which can beparticularly employed in the reforming of hydrocarbons with steam, moreespecially hdrocarbons which are heavier than methane, and in particularlight petroleum fractions of which the final boiling point is generallybetween 100 and 250 C. The treated products are mainly formed ofparafiinic hydrocarbons, but they may contain unsaturated hydrocarbonsup to a molar proportion of approximately 40%.

The generally known catalysts for these processes contain an activemetal on a refractory support and permit a high speed of conversion.

According to the conventional processes used in the reforming ofhydrocarbons, the tubes are filled with a single catalyst, as is thecase for methane. In the procedure of reforming with steam mixtures ofhydrocarbons which are heavier than methane, the use of a singlecatalyst has disadvantages. This technique frequently leads to a toohigh activity in the entry zone to the catalyst, which causes a thermalcracking and as a consequence a deposition of carbon black, and a toolow activity in the outlet zone, which supplies departing gasescontaining a fairly large proportion of residual methane.

Novel catalytic compositions with a very refractory support have beenfound according to the invention, which compositions inhibit the thermalcracking and thus the formation of free carbon, and permit of obtainingdeparting gases which contain a very low residual methane content and anadvantageous reforming with a proportion of steam which is practicallyequal to the minimum theoretical proportion.

These catalytic compositions are characterised in that they have acatalytic activity which is smaller in the entry zone of the gases to bereformed, as the hydrocarbons to be treated are more sensitive to theformation of carbon black, while the refractory oxides forming thesupport are maintained in constant ratios.

The active metal which forms part of the catalytic compositions ispreferably nickel. The nickel content in these compositions, calculatedas nickel oxide, is preferably between l% and 40% by weight.

According to a preferred variant of the invention, the

nited States Patent refractory oxides constituting the support aremagnesium oxide, zirconium dioxide and silicon dioxide, introduced insuch a way that the ratio by weight between magnesium oxide andzirconium dioxide is between 1.7 and 2 and preferably in the region of1.85, and the ratio between magnesium oxide and silicon dioxide isbetween 4.5 and 5, preferably in the region of 4.7.

The charging of the reforming zone, for example a tube, is a function ofthe type of hydrocarbon to be treated. The inlet catalytic compositions,generally the 2 to 3 first metres in the reforming tube, contain from 1%to 10% of nickel oxide.

For a light petroleum fraction containing less than 5% of unsaturatedsubstances, the inlet catalytic composition will contain about 6% ofnickel oxide.

The catalytic compositions according to the invention give excellentresults with cuts of heavier fractions as with fractions containing ahigh proportion of olefines. In the case of hydrocarbons comprising 30%of unsaturated sub stances, the nickel oxide content of the catalyst inthe first two metres of the tube will be about 4%, while it will only beapproximately 1% for fuel oils; these concentrations are defined so thatthere will be no deposition of free carbon on the catalyst.

According to the invention, the characteristics of the catalyst arechosen as a function of the evolution of the reaction, and the catalyticcompositions are disposed inside the reforming zone in the direction offlow of the gaseous mixture in several layers with an increasing nickeloxide content adapted to the evolution of the reaction. The reformingtube is filled with several dilferent catalytic compositions. In theinlet or entrance zone, the nickel oxide content is below 10%, thepurpose of this catalyst being to cause not a very efiicient cracking inthe temperature range from 450 to 550 C., in order to avoid the thermalcracking, while in the outlet or discharge zone, the content is higherand is generally of the order of to with the object of obtaining a highreforming rate.

According to one of the features of the invention, the catalyticcompositions optionally contain an activating agent in the form ofcompounds of alkali or alkali earth metals.

According to one modification of the invention, the alkali or alkalineearth metal compounds are introduced in admixture into the catalyticcompositions.

These activators may preferably be formed by a potassium sodium, bariumor calcium salt, particularly in the form of carbonates, oxides,hydroxides or nitrates, and are more particularly potassium, sodium andcalcium carbonates and barium oxide.

According to one preferred form of the present improvement, theactivator, of which the content is calculated as oxide, and the activemetal, namely the nickel, the content of which is also calculated asoxide, are in a ratio by weight which is between 0.3 and 3.

These activators are introduced into the catalytic compositions inaccordance with the present invention by one or other of the two methodsindicated below, which enable them to be easily introduced into thecatalysts.

The first of these methods consists in introducing the activator byimpregnating the active metal deposited on the support in a solutionwhich contains the activator.

According to the second method, the activator is introduced in powderform at the time of forming a paste of the catalyst.

As well as being highly efiicient, the new catalytic compositions havethe advantage of a high resistivity to sulphur. Certain catalysts permitof carrying out a good reforming with a light petroleum fractioncontaining up to ppm. of sulphur. With the majority of the nickel-typecatalysts used industrially for reforming hydrocarbons,

the presence of sulphur in the starting material to be treated causes anincrease in the methane content of the efiluent gases, at constanttemperature, and frequently deposits of free carbon on the catalyst. Onthe contrary, the low sensitivity to sulphur of the new catalyticcompositions permits a reduction of the hydrogen introduced fordesulphurising the entering gas and thus there is found an improvementby lowering the methane content and also the proportion of hydrogen ondischarge.

On the other hand, these catalysts have the advantage of an improvedresistance to the poisoning with free carbon, and concurrently providethe possibility of achieving excellent reforming results with low steamproportions, falling down to 1 expressed as H 'O/ C, the number ofmolecules of water per atom of carbon. The maximum proportion defined bythermodynamics is reached. These catalysts offer the possibility ofpermitting the desorption of the free carbon black. When the catalystbecomes clogged as a result of a reduction in the rate of admittedsteam, it is sufiicient to introduce a rate of flow of steam which ishigher than the normal rate in order to resorb the deposited carbonblack.

These three characteristics, namely, resistance to poisoning by freecarbon, low steam rate (number of water molecules per carbon atom) andhigh resistance to sulphur, constitute an important technical advanceand are of high industrial interest.

The compositions according to the invention offer yet another advantage,which is that of functioning with or without air at the inlet end of thereforming tubes and at relatively low initiating temperatures. When thereformed gas is intended for the synthesis of ammonia, the installationis preferably caused to function without air, using the air with thepost-combustion or secondary reforming in order to crack the residualmethane of the primary reforming. In certain cases concerned with thepreparation of town gas, it is preferred to introduce the air into thetube in order to obtain a certain proportion of nitrogen in the reformedgas. The catalytic compositions having a nickel oxide content lower thanat the inlet end of the reforming zone can be successfully used in bothcases.

The catalysts are supplied under any one form used in this technique;they are advantageously supplied in the form of cylinders, the height ofwhich is slightly smaller than the diameter. The choice of theirdimensions permits of reducing the pressure drops to their minimum.These catalyst cylinders have a certain number of advantages bycomparison with Raschig rings. Their mechanical resistance is greaterand they have a smaller tendency than the Raschig rings to becomecharged with carbon black.

It has been observed than when a catalyst starts to become charged withcarbon deposit, it is the central hole which is clogged, then a film isformed on the outside and the dust particles or carbon black formedduring the reaction tend to become deposited inside the holes of theRaschig rings, where the velocities are much lower than on the outside,particularly when the axes of the holes are not vertical.

The carbon black which adheres to the wall of the central hole can onlybe removed with difliculty, while that which appears on the outside ofthe particle is entrained by the gaseous fiow and can be attacked bymixture during its transport.

Examples which illustrate the invention in a non-limiting manner aregiven below.

EXAMPLE 1 (a) Catalytic composition A Nickel (NiO) from 6 to 10%,preferably about 8%, magnesium oxide (MgO) from 50 to 54%, preferably52%, zirconium dioxide (ZrO from 24 to 34%, preferably 28%, silicondioxide (SiO from 9 to 12%, preferably 11%.

(b) Catalytic composition B Nickel (NiO) from 2 to 6%, preferably 4%,magnesium oxide from 53 to 56%, preferably 55%, zirconium dioxide from28 to 32%, preferably 30%, silicon dioxide from 10 to 12%, preferably11%.

(c) Catalytic composition C Nickel (NiO) from 3 0 to 35%, preferably32%, magnesium oxide from 35 to 40%, preferably 38%, zirconium dioxidefrom 20 to 27%, preferably 21%, silicon dioxide from 6 to 10%,preferably 8%.

The nickel can vary from 1 to 40%, the other constituents being in thefollowing ratios:

Magnesium oxide 1.7 '00 2, preferably Magnesium oxide 4.5 5, preferably1.7

EXAMPLE 2 EXAMPLE 3 A tube with an internal diameter of 95 mm. ischarged with a catalyst having 8% of NiO for a height of 3.50 metresstarting from the inlet end, then with a catalyst having 32% of NiO overa height of 3.50 metres, starting from the middle, these two catalystsbeing in the form of cylinders with a diameter of 15 mm. A lightpetroleum fraction, of the empirical formula C H with a boiling pointbetween 40 and C., is then introduced downwardly into the tube at a rateof 35 kg. per hour.

In the series of tests, the results of which are set out in thefollowing table, the values shown for the steam rate, which is the ratioof the number of water molecules to a carbon atom, are between 2.35 and4.3. Certain operations are carried out in the presence of a rate of airflow of 25 m. /hour and the others in the absence of air. The admissiontemperatures of the mixture are between 435 and 500 C. The pressure atthe outlet end of the tube in gauge bars varies from 10 to 19.

1120/0 molar Rate of air flow Composition of the departing gas Percent(Calculated as dry gas) CO: CO CH4 C2110 in actual bars EXAMPLE 4 (a)Catalytic composition A Nickel in NiO from 6 to 10%, preferably about8%, magnesium oxide (MgO) from 50 to 54%, preferably about 50.5%,zirconium dioxide (ZrO from 24 to 34%, preferably about 28%, silicondioxide (SiO from 9 to 12%, preferably about 9%, potassium carbonate inK from 3 to 6%, preferably about 4.5%.

This composition was obtained by alkalisation of the catalyticcomposition A by soaking in a potassium carbonate solution.

(b) Catalytic composition A This catalyst has the same composition byweight as the above catalyst A but it differs therefrom by theintroduction of the activator in the form of potassium carbonate as apowder at the time of forming the catalyst paste.

(c) Catalyst composition A Nickel in NiO from 6 to 10%, preferably about8%, magnesium oxide (MgO) from 50 to 54%, preferably about 50%,zirconium dioxide (ZrO from 24 to 34%, preferably about 31%; silicondioxide (SiO from 9 to 12%, preferably 9%, barium oxide (BaO) from 1.5to 4%, preferably about 2%.

This composition was obtained by barium oxide in powder 'form beingintroduced at the time of forming a paste of a catalytic composition ofthe type A.

(d) Catalytic composition A,

Nickel in NiO from 6 to 10%, preferably about 8%, magnesium oxide (MgO)from 50 to 54%, preferably about 50%, zirconium dioxide (ZrO from 24 to34%, preferably about 29%, silicon dioxide (SiO from 9 to 12%,preferably about 9%, sodium carbonate (Na O) from 2 to 4% preferablyabout 4% This composition can be obtained with excellent results byimpregnation or by introduction of sodium carbonate in powder form.

(e) Catalytic composition A Nickel in NiO, preferably about 8%,magnesium oxide (MgO) preferably about 50%, zirconium dioxide (ZrO-preferably about 27.5%, silicon dioxide (SiO preferably about 9%, bariumoxide (BaO) preferably about 1.5%, sodium carbonate (Na O) preferablyabout 4%.

(f) Catalytic composition B mixture (light petroleum fraction andhydrogen) is magnesium oxide (MgO) from 53 to 56%, preferably about 53%,zirconium dioxide (ZrO form 28 to 32%, preferably about 30%, silicondioxide (SiO from 10 to 12%, preferably about 10%, potassium carbonatein K 0 from 3 to 6%, preferably about 3%.

This composition was obtained by alkalisation of the catalyticcomposition B, by impregnation of the catalyst cylinders in a solutionof potassium carbonate.

(g) Catalytic composition B This catalyst has the same composition byweight as the above catalyst B but it differs therefrom by introducingthe activator as a powder at the moment of forming a paste of thecatalytic composition.

(h) Catalytic composition B Nickel in MD from 2 to 6%, preferably about4%, magnesium oxide (MgO) from 53 to 56%, preferably about 53%,zirconium dioxide (ZrO from 28 to 32%, preferably about 31%, silicondioxide (SiO from 10 to 12%, preferably about 10%, barium oxide (BaO)from 1.5 to 4%, preferably about 2% (i) Catalytic composition 3.,

Nickel NiO from 2 to 6%, preferably about 4%, magnesium oxide (MgO) from53 to 56%, preferably about 53%, zirconium dioxide (ZrO from, 28 to 32%,preferably about 29%, silicon dioxide (SiO from 10 to 12%, preferablyabout 10%, sodium carbonate (Na O) from 2 to 4% preferably about 4% (j)Catalytic composition B Nickel in NiO preferably 4%, magnesium oxide(MgO) preferably 53%, zirconium dioxide (ZI'OZ) preferably 10%, silicondioxide (Si0 preferably 10%, barium oxide (BaO) preferably 1.5%, sodiumcarbonate (Na O) preferably 3.5%

EXAMPLE 5 ladium and zinc oxide catalyst functioning at 320 C.

The mixture of steam and gaseous hydrocarbon then passes into aring-type reactor formed of two tubes. The temperatures are keptconstant by regulators acting on 5 heating resistances. By this means,Whatever may be the rate of flow of the light petroleum fraction and theproportion of steam (ratio of the number of water molecules to a carbonatom), the temperature range inside the reactor remains substantiallythe same, the different temperatures extending from approximately 500 to760 C.

The rate of flow of the light petroleum fraction is in the region of 30cc. per hour and the rate of flow of hydrogen for the desulphurisationis between 7 and 25 litres per hour. The proportion of steam was variedbetween 3 and 1.

These reforming tests were carried out at atmospheric pressure. Thecatalysts used correspond to the catalytic compositions of Example 4,and also the catalytic composition A of Example 1,

and the catalytic composition A with addition of antimony oxide in theform of SbO 2.5 to 3% (a) Study of the catalytic activity of thecatalytic composition A under the conditions previouslydescribed.--Under the best treatment conditions, 15% of the enteringlight petroleum fractions is not reformed.

7 The departing gas contains C C and C H hydrocarbons. The lowering ofthe proportion of steam from The results of the tests in this exampleare set out in the following table.

Corrc- HzO/C for Minimum spending Maximum Corrcformation 4, molar ofethylene spending of carbon Catalytic composition Percent Ii'zO/OPercent HzO/O black Influence of the sulphur 1 A: 4. 5 1 2 2. 5 1 A 1.7 1. 2 1. 2 A4- 6 1. 3G 1. 3 Negligible. A 0. 3 1. 2 1. 2 B 2 1. 3 0.5 1. 3

A+antimony oxide Czimscs the formation of free carbon.

l Does not reform. 2 Trzaces. 3 Constant content.

3 to 2 causes a lowering of the quantity of reformed petrol. Inaddition, there was observed an increase in the pressure drop at thesteam proportion 2. After leaving the catalyst of the reforming zone,the presence of a white deposit was found on its surface, but noformation of carbon black. This catalyst gave a not negligible contentof ethylene in the departing gas.

(b) Study of the catalytic activity of the composition A under thecondition described above.Using this catalyst, activated with potassiumcarbonate introduced in powder form at the time of making a paste of thecatalyst containing the active metal, even at a steam proportion as lowas 1, there was obtained a total reforming of the treated lightpetroleum fraction and a departing gas which contained only 0.1 to 2% ofethylene.

It is necessary to reduce the steam proportion to 1 in order to cause aclogging by formation of carbon black.

(c.) Study of the activity of the catalytic composition A under theconditions previously described.-n this catalyst, even at a steam rateor proportion as low as 2.2, the entire light petroleum fraction isreformed and the departing gas contains less than 0.5% of ethylene.Below this rate and down to 1.3 (minimum rate investigated), traces of CC and even C hydrocarbons were found.

On a light petroleum fraction not desulphurised, down to 60 p.p.m. ofsulphur and for steam rates which are between 1.4 and 1.7, the reformingwas good, with traces of C and C hydrocarbons.

(d) Study of the activity of the catalytic composition A, under the sameconditions as used in the preceding tests.On this catalyst, the lowestadmissible steam rate was 1.20 without increasing the pressure drop;below this level, carbon black appeared. It is necessary to note thatthis catalyst leads to a departing gas having the lowest proportion ofmethane and an almost complete absence of C and higher hydrocarbons.

(e) Study of the activity of the catalytic composition B, underconditions similar to those of the preceding tests.0n this catalyst,down to a steam rate or proportion as low as 1.3, all the lightpetroleum fraction is reformed, and the departing gas contains littleethylene. However, it was observed that, with a light petroleum fractioncontaining a few p.p.m. of sulphur, the clogging is only produced onreaching a steam proportion of 1.3, whereas with 95 p.p.m. of sulphur,the clogging appeared with a steam proportion of about 2.4.

(f) Study of the activity of the catalytic composition A, to whichantimony oxide is added, under the preceding conditions.With this typeof activator, the light petroleum fraction is not completely reformed.There is still some of the initial petrol in the effluent gas andanalysis by chromatography shows that there are C C and even Chydrocarbons present.

The reforming tube is clogged in 2 hours with a steam proportion ofabout 2, as molecules of water per atom of carbon.

From reading this table, it is clear that the action of sulphur seems tobe of little effect on the catalytic composition A.;, whereas it causesa formation of carbon black on the composition B containing 4% ofnickel, in NiO form, without activating additive.

As regards the formation of free carbon, it can be noted that the lowerlimit of the admissible steam proportion varies from 1.2 to 1.3 for thecatalytic compositions B, A and A containing respectively 4% and 8% ofnickel and sodium carbonate as activator in the case of the lastcomposition, while the limit of this steam proportion reaches 1 for thecomposition A having 8% of nickel activated by potassium carbonateintroduced in powder form.

The results of these tests permit the conclusion to be reached that thevery active catalyst A with 8% of nickel causes a formation of carbonblack at a steam proportion higher than the less active catalyticcomposition A and also provide the possibility of estimating that thiscomposition A2 would probably be most suitable for the heavy fractions,and particularly for the reforming of petrols which are sensitive tothermal decomposition. On the contrary, the composition A should be verysuitable for reforming light fractions.

In respect of 5 of the catalytic compositions previously studied inconnection with the reforming of a petrol fraction of empirical formulaC H at atmospheric pressure, the curve of the methane content has beenplotted as a function of the steam proportion.

In FIGURE 1 of the accompanying drawing, in which the steam proportion HO/C, number of water molecules per carbon atom, has been plotted asabscissae, and the percentages of methane have been plotted asordinates, it is shown that the 5 curves corresponding to thecompositions have different paths.

The curves 5, 4 and 3 for the compositions A A and B have the same path,the maximum methane content being of the same magnitude, particularlyfor the first two. On the contrary, as regards the composition A, thereis found a decreasing function which is represented by the curve 1, ofwhich the minimum value of methane is clearly lower than for thecompositions A and B repre sented by the curves 2 and 3; under theconditons of the test, the composition A is more active than the othercatalysts.

As regards the maximum ethylene content, the curves have the same pathfor the different compositions, with the exception of the curvecorresponding to the composition A, which only produces traces ofethylene.

In FIGURE 2 of the accompanying drawing, in which the percentage ofsulphur expressed as p.p.m. is plotted as abscissae and the percentageof methane is plotted as ordinates, there is represented the variationsin the percentage of methane in the effluent gases as a function of thesulphur for the catalytic composition A.,,. The temperature of thecatalyst mass varied from 550 C. at the inlet end to 760 C. at theoutlet end of the tube for tests at atmospheric pressure. The content ofmethane has varied slightly as the sulphur content in the lightpetroleum fraction increased. 6.4% of methane is noted for a sulphurcontent lower than 1 ppm, and for a steam proportion in the region of1:6 expressed as H O/C; for 20 ppm. of sulphur, this methane ratioincreases to 7.4%, and for 60 ppm, it increases to 8.5%.

EXAMPLE 6 Using an industrial tube charged with the catalyticcomposition A, first of all a desulphurised light petroleum fraction wasreformed, and then the content of sulphur was increased whileprogressively reducing the recycling hydrogen for the catalytictransformation of the sulphur into hydrogen sulphide, which is absorbedby a zinc mass. The decrease in the recycling hydrogen is not initiallyexpressed by an increase in the content of sulphur, but below a certainrecycling rate, sulphur appeared at the inlet end of the reforming tubeand at the outlet end. Finally, after completely shutting 011 therecycling, all of the entering sulphur, that is to say, 15 p.p.m., istransferred to the catalyst.

EXAMPLE 7 In an industrial tube containing 60 litres of catalyst withthe composition A, there are caused to pass 60 litres per hour of alight petroleum fraction of the approximate empirical formula C H with asteam rate H O/ C of 2.9.

The installation operates under a pressure of 30 bars at the outlet endof the tube, the temperatures inside the tube ranging from approximately500 to 800 C. The pressure drop in the tube is 800 g./cm. A valveregulating the rate of flow of steam is closed for 2 minutes. The lightpetroleum fraction continues to enter the tube in the absence of steamand it is cracked into carbon and hydrogen. The carbon is deposited onthe catalyst, particularly in the first third of the mass. Steam is thenonce again supplied into the tube at a rate higher then the nominal rate(proportion of H O/C of 3.7). There is observed a stabilisation of thepressure drop at 1400 g./cm. then a fairly rapid decrease. The steamrate is then brought to its nominal value end, over a period of about 20hours, the pressure drop decreases slowly until it reassumes its nominalvalue.

The results which are obtained are indicated by FIG- URE 3 of theaccompanying drawing, in which the time in hours (T) is plotted asabsissae and the pressure drop (AP) in grams/cm? is plotted asordinates.

The rectilinear portion OA represents the stable running at 30 bars withthe steam rate H O/C=2.9, the vertical line AB shows the running withoutsteam, the rate of flow of the light petroleum fraction being kept atthe nominal value. The portion BC of the curve corresponds to thestopping of the increase in pressure drop by introduction of steam atthe rate H O/C=3.7, while the descending line CD represents theresorption of a quantity of carbon black formed on the catalyst at thesteam rate H O/C=3.7, and the line at the end the resorption of thecarbon black at the normal steam rate H O/ C of 2.9.

The test carried out in this example leads to the following conclusions:

In the event of an incident in the steam system, the catalyst is able tocrack a light petroleum fraction in the absence of steam without beingdestroyed. If the incident lasted very long, the tube would becomecompletely clogged and it would then be impossible to cause the gases tocirculate. It would be necessary to discharge the catalyst, remove thedust and recharge it.

A pressure drop caused by a complete lack of steam for a short period oreven by a reduced steam rate for a longer period, can be resorbed, byincreasing the rate of flow of steam.

An incident of the type previously described does not lead in most casesto a stoppage of the installation, this being of particular interest forlarge-capacity installation.

What is claimed is:

1. Catalytic compositions suitable for use in the steam reforming ofhydrocarbons heavier than methane, comprising nickel as the active metalbetween 1-40% 'by weight calculated as nickel oxide, and a supportconsisting essentially of a mixture of silicon dioxide, magnesium oxideand zirconium dioxide, the magnesium oxide to zirconium dioxide ratio byweight being between 1.7 and 2, and the magnesium oxide to silicondioxide ratio by Weight being between 4.5 and 5.

2. Catalytic compositions according to claim 1, wherein the ratio byweight of magnesium oxide/Zirconium dioxide is approximately 1.85, andthe ratio by weight of magnesium oxide/silicon dioxide is approximately4.7.

3. Catalytic compositions according to claim 1, wherein the content ofactive metal, calculated as nickel oxide, is between 6% and 10%.

4. Catalytic compositions according to claim 1, wherein the content ofactive metal, calculated as nickel oxide, is between 2% and 6%.

5. Catalytic compositions according to claim '1, wherein the content ofactive metal, calculated as nickel oxide, is between 30% and 35%.

6. Catalytic compositions according to claim 1 further containing anactivator in the form of alkali or alkaline earth metal compounds, theproportions, expressed as oxides, of activator to oxide of nickel beingbetween 0.3 and 3.

7. Catalytic compositions according to claim 6, wherein the alkali andalkaline earth metal compounds are used in admixture.

8. Catalytic compositions according to claim 6, wherein the activator isa member of the group consisting of the salts of potassium, sodium andbarium.

9. Catalytic compositions according to claim 8, wherein the activator isa member of the group consisting of carbonates and oxides.

References Cited UNITED STATES PATENTS 2,056,911 10/1936 Schiller et al.23-212 2,639,223 5/1953 Shapleigh 252-457 2,830,880 4/1958 Shapleigh23-212 2,943,062 6/1960 Mader 48-196 3,119,667 1/1964 McMahon 23-2123,132,010 571964 Dwyer et a1 23-212 3,140,249 7/ 1964- Plank et al. 208-OTHER REFERENCES Thorpes Dictionary of Applied Chemistry, vol. X'I, p.11101l1l, Longhams Green and C0,, N.Y.

DANIEL E. WYMAN, Primary Examiner P. E. KONOPKA, Assistant Examiner US.Cl. X.R.

Po-ww UNITED STATES PATENT OFFICE 5 9 CERTIFICATE OF CORRECTION PatentNo. 3457'l92 DatedJ July 1 1969 I J. HOUSSET ET AL Inventofls) It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 5, line 61, delete "mixture (light petroleum fraction andhydrogen) is" and substitute -Nickel in N10 from 2 to 6%, preferablyabout 4%- (typed specification page 10, line 19) SIGNED AND SEALED(SEAL) Attest:

mmxm E. sommnm, 1!. Edward M. Fletcher, J Conmissioner 01f, PatentsAttesting Officer

